I'm new at this, can someone help?

I need to show this led finger light with a white background. But the light needs to be on and show a little color on that white background. If I just use a brush and white out some area around the light hitting the table then it does not look very good. I want to make a great looking photo to put on the front of this website. I would appreciate any help at all. There is a photo now on the front of this website www.lducompany.com of the finger light but they want me to change it to have a white back ground but show the color light. Thank you.